On Fri, 09 Jan 2009 15:31:57 -0000, John C Klensin <[email protected]> wrote:
> Now, if what you are really asking about is my personal > opinion... At this point, I believe we would be better off > > * without Downgrade as specified > * pushing for rapid implementation and deployment of an > internationalized email solution that is free of > in-transit downgrading and the associated syntax, > header, digital signature, etc., issues > * concentrating our efforts on address downgrading > procedures that could be applied at the endpoints -- > the sending MUA or submission MTA and after SMTP final > delivery, rather than figuring out how to make > in-transit work > * getting more specific about the cases in which > in-transit downgrading might be needed and how they can > best be avoided by careful configuration. Yes, that is a situation we can hope to arrive at eventually, but perhaps not so soon as you seem to imply. For sure, there would have been huge outcries if we had tried to introduce it with no downgrading right from the start, so we had to do it that way. What happens next will depend on how successful and how widely adopted implementation turns out to be. and we shall not know that for a few years yet. But it would probably be useful to mention in some document somewhere that there is an intention that downgrading can eventually be phased out. MIME got itself into a mess when it invented 8BITMIME, by saying that implementations offering it MUST downgrade to 7bit if the next hop does not advertise that extension. BUT, in practice, you would be hard pressed nowadays to find a working server that was NOT 8-bit clean, at least for bodies (and even 8bit cleanliness in headers is becoming near-universal). But, of those 8-bit-body-clean implementations, some do not offer the downgrqde service and, of those, some still advertise 8BITMIME rergardless (e.g. qmail), whereas others (e.g. EXIM) refrain from advertising it (though EXIM does allow individual admins to override that restraint). The result of all that, as it turns out, is that 8bit stuff propagates just fine, even via qmail, except that much unnecessary downgrading to 7bit takes place on account of implementations like EXIM which do it but don't advertise it. And this unnecessary downgrading brings its own problems, such as failure of s-MIME and DKIM signatures. Indeed, there is just too much Q-P and base64 stuff flowng around these days, most of it not really necessary. So we need some sort of "sunset" clause that indicates that this state will not last for ever. But at least, with IMA, we have quite properly arranged that bouncing is an acceptable alternative to downgrading, and this may well lead to the development of large cimmunities within which downgrading is not provided, and I have no problem with that. -- Charles H. Lindsey ---------At Home, doing my own thing------------------------ Tel: +44 161 436 6131 Web: http://www.cs.man.ac.uk/~chl Email: [email protected] snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K. PGP: 2C15F1A9 Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5 _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
